This invention relates to treating barren earthen areas for inhibition of air and sun spoilation, and more particularly it relates in one preferred embodiment to preventing fires in combustible earthen banks such as burning coal refuse piles and inactive coal refuse banks and the like.
In one specific area of application, namely burning or combustible coal spoil piles and other combustible mine refuse dumps, the uncontrolled burning of such dumps has created a severe pollution and environmental control problem in many places. In 1964 the United Staes Bureau of Mines estimated that there were then almost 500 burning coal refuse banks averaging 14 acres per bank. More recently the situation has become worse. As defined by the Bureau of Mines, refuse banks are to be considered as any combination of carbonaceous waste and materials associated with rock, shale, culm, boney, slate, clay and related material associated with or near a coal seam which are removed from the mine or separated from the coal during the cleaning or preparation operations. Such earthen refuse is deposited in a pile to form a bank. The banks are loose on the surface, but as subsequent layers are added compaction takes place and heat is generated by atmospheric exposure. Many components of the bank are combustible; and with air permeating into the bank, spontaneous combustion occurs when air enters in sufficient quantities to support and promote combustion. When "hot spots" are detected, or the refuse banks begin to smolder and burn, men and equipment must be moved to the site of the fire and must break into the burning pocket within the bank. The "hot spot" must then be isolated and cut away from the bank or extinguished and the pocket then sealed, generally in practice, by covering with a minimum two-foot layer of compacted very finely divided inert material. Still, after such sealing measures, banks frequently reignite either by failure to completely cut out and isolate the complete "hot spot" or by the ignition of adjacent areas to the pocket previously extinguished. Such banks tend to be very large with steep slopes, and it is quite difficult and frequently hazardous to move men and equipment about them.